Special News10 (24-hour Bath)

1. Bacteriological Water Quality Standard of "24-hour Bath" (water in bathtub)

Legionella, which many manufacturers of the "24-hour bath" have not set as an index of the bacterial contamination and which was hard to be identified, should be set to, at least, an object of the bacteriological water quality management in future and a disinfection device suited thereto should be equipped.

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2. Bacteriological Safety Measures of Water System

1. 1.To reduce the risk of the infectious disease related to the bathing action, the sanitary management and disinfection are required for the bathtub inner wall, a pipe system, bathwater, and highly frequently splashed parts.
2. 2.It is impossible in the present state to express the relation between the abundance of the Legionella in the bathwater and the infection to the human by a "threshold (minimum value of the dimension and the intensity of an action necessary for some system showing a notable reaction)" having the academic sureness.
   To aim non-detection ^(note) is desirable, however, it is left to the judgment and responsibility of the manufacturer that what kind of performance should be applied to the product.
   The risk of the disease occurrence whose infectious origins are equipment and devices manufactured by the manufacturer shall be shouldered by the manufacturer and the responsibility of the correctness of the "threshold" set by the manufacturer should be shouldered by the manufacture.

1. (Note)The detection method for the Legionella is based on the method described in an appendix of "Guideline for Prevention of Legionellosis" (compiled under the supervision of Planning Division, Environmental Health Bureau, Ministry of Health and Welfare and published by Building Management Education Center).
   According to the method, the lowest detection limit is 10 cfu (colony forming unit) per test water 100 ml.

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3. Present States and Problems of Bathwater of "24-Hour Bath"

As information of consumer in choosing product, it is important that

• 1.as for the "24-hour bath" with no disinfection device, the reason why the maker thinks that no disinfection device is required for the bath,
• 2.as for the "24-hour bath" with a disinfection device, conditions of the disinfection function assessment,
• 3.in a case where a disinfection device is installed after a biological treatment, the removal method of the exfoliated materials from a biological treatment device,
• 4.setting methods of the disinfection conditions, demonstration results, and
• 5.implementation of sequential monitor by a water quality monitor, and the results shall be released.

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4. Consumer Services

For the consumer, following services are required.

• 1.Provision of proper information of products to the consumer.
  The manufacturing and sales companies shall provide the objective information of the follows to the consumer.
  1. 1.Disinfection methods, disinfection effects, and assessment methods.
  2. 2.Performances and characteristics of the products such as matters necessary for working the original function of the device (frequency of changing water, frequency of exchanging a filter, etc.).
• 2.Calling attention to the consumer using the "24-hour bath" at present
  • 1.For minimizing the risk of occurrence of the legionellosis caused by the "24-hour bath",
    1. 1. The wall surface of a bathtub should be wiped out to remove "slime" (biomembrane) so as not to accelerate the formation of "biomembrane" and the reproduction of bacteria on the inner wall of the bathtub and the pipe of the device inside.
       Though the removal frequency is differed according to respective devices, if you feel the "slime" to some extent, remove it within the day.
    2. 2. The pipes should be cleaned according to the instruction of the an instruction manual and at the same time, is required to be effectively disinfected and surely exterminate the Legionella. It is desirable to ask the measures to the manufacturer or the selling agency and perform effective disinfection at all times.
  • 2.It is a high risk that the Legionella is infected to the human respiratory organ by inhaling aerosol (micro water particles incapable of being identified by the naked eyes) including the Legionella so that the number of the Legionella should be suppressed by the "biomembrane" preventive measures and the follows should be performed to reduce the generation amount of the aerosol and the risk of its inhalation.
    1. 1. Avoid using a bubble generator.
    2. 2. Do not take a shower bath using the bathwater.
    3. 3. As for the shower other than 2, occasionally clean the showerhead.

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5. Trial Purchase Test Results for Quality and Performance

1. 1.The trial purchase test was performed because the actual states of the "24-hour bath" are still not known well and reports such as an ignition accident and the turbidity of the bathwater were collected to the accident information collection system of the Ministry.
2. 2.The tested products were set to 9 brands of the bathroom installation type whose numbers of sales are outnumbered among those on the domestic market.
3. 3.The tested items were
   1. 1. structure,
   2. 2. electric safety,
   3. 3. power consumption,
   4. 4. accuracy of controlling bath water temperature,
   5. 5. accuracy of displaying bath water temperature,
   6. 6. increase rate of bathwater temperature under high room temperature,
   7. 7. safety in lowering the water level and in opening/closing the inlet port,
   8. 8. purification performance of bathwater,
   9. 9. disinfection performance of Escherichia coli,
   10. 10. attentions in using, and
   11. 11. contents of instruction manual.
4. 4.The rest results showed that there were no problem in particular in their structures, electrical safety, power consumption, etc., however, some of the attentions and the instruction manuals did not state items related to the safety use.
   As for the purification performance, the turbidity and the number of Escherichia coli in the bathwater were measured.
   As for the turbidity, some of them were at first nebular but it was reduced in the next day.
   In this test, the whole purification performance including the Legionella was not assessed.